Roe deer are becoming more and more common and can be found in most small patches of woodland as well as out in the fields. Sooner or later a working dog is going to bump into one or a family group and if you have not trained some sort of control then a wild chase can occur. This is not only dangerous it can also continue for miles where upon your dog could find itself lost.
Dogs need to understand that deer are not game especially if hunting with a falcon or hawk, if you were training a Large Munsterlander for deer stalking then this is very different as they are superb at tracking and will find wounded deer very efficiently.